How do you get the diagnostic codes on a 2000 Cadillac STS?

To retrieve diagnostic codes from a 2000 Cadillac STS, you can use an OBD-II scanner. First, connect the scanner to the OBD-II port located under the dashboard near the driver's seat. Turn the ignition to the "On" position without starting the engine, then follow the scanner's prompts to read the diagnostic trouble codes (DTCs). Alternatively, you can perform the "key-on, engine-off" procedure by turning the ignition on and off three times quickly, which may display codes on the dash, though using a scanner is more reliable.